我修改this server以使用gen_tcp:recv
以便将数据包的字节数限制为50.我注释了行inet:setopts(Socket, [{active, once}]),
,因为gen_tcp:recv
应该是{active,false}
。这是客户端erl shell
2> cp3:client().
exit
3>
这是服务器端erl shell
4> cp3:server().
Started Server:
<0.46.0>
Accept Server:
Pid <0.48.0>
Connection accepted
Accept Server:
Loop Server:
5>
我还想知道如果{tcp_closed, Socket}
没有创建套接字,我怎么知道套接字是否以返回值gen_tcp:recv
关闭?
-module(cp3).
-export([client/0, server/0,start/0,accept/1,enter_loop/1,loop/1]).
client() ->
{ok, Socket} = gen_tcp:connect("localhost", 4001,[list, {packet, 0}]),
ok = gen_tcp:send(Socket, "packet"),
receive
{tcp,Socket,String} ->
io:format("Client received = ~p~n",[String]),
io:format("Client result = ~p~n",[String]),
gen_tcp:close(Socket)
after 1000 ->
exit
end.
server() ->
Pid = spawn(fun()-> start() end),
Pid.
start() ->
io:format("Started Server:~n"),
{ok, Socket} = gen_tcp:listen(4001, [binary, {packet, 0},{reuseaddr, true},{active, false}]),
accept(Socket).
accept(ListenSocket) ->
io:format("Accept Server:~n"),
case gen_tcp:accept(ListenSocket) of
{ok, Socket} ->
Pid = spawn(fun() ->
io:format("Connection accepted ~n", []),
enter_loop(Socket)
end),
io:format("Pid ~p~n",[Pid]),
gen_tcp:controlling_process(Socket, Pid),
Pid ! ack,
accept(ListenSocket);
Error ->
exit(Error)
end.
enter_loop(Socket) ->
%% make sure to acknowledge owner rights transmission finished
receive ack -> ok end,
loop(Socket).
loop(Socket) ->
%% set socket options to receive messages directly into itself
%%inet:setopts(Socket, [{active, once}]),
io:format("Loop Server:~n"),
case gen_tcp:recv(Socket, 50) of
{ok, Data} ->
case Data of
<<"packet">> ->
io:format("Server replying = ~p~n",[Data]),
gen_tcp:send(Socket, Data),
loop(Socket)
end;
{error, Reason} ->
io:format("Error on socket ~p reason: ~p~n", [Socket, Reason])
end.
答案 0 :(得分:4)
我对你的问题不太清楚,但上面的代码不起作用。希望以下解答您的问题。您的tcp接收case gen_tcp:recv(Socket, 50) of
有一个错误。它等待50个字节读取。查看gen_tcp:recv/2的文档。更改长度(封隔器6的长度,但最好是0)以接收所有字节。
该值不限制数据的大小,但在收到长度为50的数据之前,它不会发回数据。相反,您可能需要接受然后再检查它。